Drivers vanished from system preferences

Hi guys,

Some time ago and by no apparent reason, my drivers' icons vanished from System preferences in Yosemite 10.10.3. This lead to having to reinstall my Wacom tablet drivers every time I restart the computer, it is as if the computer deletes/forgets the data on those drivers on any reboot.

Any idea as to how to proceed with this? Should I reinstall Yosemite?

Thanks,

Mikel